1. Field of the Invention
This invention pertains to a new threaded joint for pipes which is provided with a device to oppose over-screwing or unscrewing in order to avoid undesirable and uncontrolled rotations of one of the tubular elements with respect to the other after the two tubular elements have been joined by the joint in accordance with the invention.
2. Discussion of the Background Art
The majority of presently available joints are not provided with devices that oppose over-screwing or unscrewing, and it suffices to apply a torque greater than the torque which was used for the assembly of two tubular elements in order to cause rotation of one element with respect to the other, this rotation being effected in the direction of complementary screwing, or in the direction of unscrewing.
However, in certain circumstances it is necessary to prevent any relative rotation of one tubular element with respect to another after tightening of the joint to the desired torque, such unscrewing or over-screwing capable of being caused in operation due to the forces and displacements to which the pipes are subjected, forces and displacements which can create torques greater than the coupling torques. Such unscrewing or over-screwing may also be produced in particular because of vibrations with the applied torques which can in this case be less than the torques used in the initial connection.
Generally, one will resort in this case to welded joints, which of course have the disadvantage of requiring a considerably heavy material. These joints cannot be taken apart and are used only with easily welded materials.